The present invention relates to hollow plastic containers and, more particularly, to blow molded plastic containers with self-supporting bases. The base has sufficient strength to withstand internal pressures like those encountered in the packaging of carbonated beverages and the like, and in addition has distinct supporting feet which enable the container to stand without rocking.
With movement to plastic bottles for packaging carbonated beverages, the art has moved to plastic containers with self-supporting bases. Such a container must be able to withstand the internal pressure necessary to maintain the desired carbonation. Such a pressure is on the order of 75 p.s.i.
Several types of containers exist in the art that include integral bases with molded bottom configurations. These types of containers are illustrated in the following patents: U.S. Pat. Nos. 3,403,804, issued Oct. 1, 1968 to Colombo, entitled "Blown Bottle of Flexible Plastic"; U.S. Pat. No. 4,249,667, issued Feb. 10, 1981 to Pocock et al, entitled "Plastic Container with a Generally Hemispherical Bottom Wall Having Hollow Legs Projecting Therefrom"; U.S. Pat. No. 3,935,955, issued Feb. 3, 1976 to Das, entitled "Container Bottom Structure"; U.S. Pat. No. 4,108,324, issued Aug. 22, 1978 to Krishmakumar, et al, entitled "Ribbed Bottom Structure for Plastic Container"; U.S. Pat. No. 3,871,541, issued Mar. 18, 1975 to Adomaitis, entitled "Bottom Structure for Plastic Containers"; and U.S. Pat. No. 3,598,270, issued Aug. 20, 1971 to Adomaitis et al, entitled "Bottom End Structure for Plastic Containers". While these containers are known there still exists a need for a container of this type which requires a reasonable amount of material in the base, withstands internal pressures and will stand upright with out rocking.
The present invention provides the art with a container having a tubular body and an integral base, the junction of the two having a smooth, continuous exterior surface. The present invention eliminates any sharp bends deviations, or the like at the junction of the body and base. The present invention provides the container with good distribution of plastic throughout the container surface. Also, the present invention eliminates stress cracks and enables the use of a minimum amount of plastic material to mold the container. Also, when the container is full of a carbonated beverage or the like, the container will withstand the pressure necessary to maintain carbonation and will exhibit a very sturdy and rigid outer body. Once the beverage has been removed from the container, the container is very flexible and enables the container to be discarded and the plastic re-cycled.
Accordingly, the present invention provides an improved blow molded plastic container having the above advantages. The container includes a tubular body terminating at its lower end in an integral base. The base includes a truncated frusto-conical shape inner wall projecting into the interior of the tubular body. The frusto-conical shaped inner wall terminates at its upper end in a substantially planar top surface. Outwardly of the inner wall the container has a downwardly concave annular chamber bounded on the radially inner side by the inner wall of the base and on the radially outer side by the outer wall of the base. A plurality of ribs are formed radially about the base between the frusto-conical inner wall and the outer wall of the base. The ribs are in a plane below the planar top surface of the inner wall and form in the base a plurality of feet arranged in a circular formation and symmetrical with respect to the container axis. The feet are formed between the ribs and have a wide dimension in a direction circumferentially of the base to provide firm support for the container when standing.
From the subsequent description and claims taken in conjunction with the accompanying drawings, other objects and advantages of the present invention will become apparent to those skilled in the art.